An image forming apparatus is proposed that has a function of preventing copying (printing) of copy-prohibited documents represented by bank notes, securities, etc.
Japanese Laid-Open Patent Publication No. 2005-20334 discloses the image forming apparatus that, when setting the copy-prohibited document on a document reading device (scanner) and trying to copy the document, is capable of not only preventing copying of the document but also physically preventing taking-out of the thus set copy-prohibited document.
In the image forming apparatus disclosed in Japanese Laid-Open Patent Publication No. 2005-20334, a locking claw which is disposed at a document cover portion (document mat) of the image forming apparatus and used for fastening the document cover portion to a document setting portion of the document reading device fastens (locks) the document cover portion to the document setting portion engaging with a locking portion disposed at the document setting portion.
Therefore, in the image forming apparatus when the copy-prohibited document is a paper with the thickness of the order of several millimeters, the document set on the document reading device can be physically prevented from being taken out.
However, when the copy-prohibited document is, for example, a thick document such as a book, the locking claw can not engage with the locking portion disposed at the document setting portion.
As a result, the document cover portion can not be fastened to the document setting portion and the thick document can not be physically prevented from being taken out from the document setting portion.